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Full text of "The manufacture and properties of iron and steel"

METHODS OF MANUFACTURE.                              223
be a similar absorption of energy.   In the present case it will be as follows:
Absorbed by silicon.............     10X931=    9,310
Absorbed by carbon............   37.5X705= 26,438
Total...................                      35,748
Brought down from above.....                        90,739
Total   absorption   ........                       126,487
To translate these figures into a simpler form it has been shown that if the metalloids in molten pig-iron are to be oxidized by iron ore alone without assistance from the flame of the furnace, then every ton (2240 pounds) of pig-iron will require 500 pounds of iron ore, and the reaction will absorb so much heat that the metal will be 770 C. (say 1380 F.) colder at the end of the work. Of this total of 500 pounds of ore, 367 pounds will be taken care of by the carbon, while 80 pounds will furnish the oxide of iron to form a
This assumes that the ore is added in a liquid state, so that no heat is necessary to heat or melt the addition. It does not assume that the carbon is oxidized to carbonic acid (C02), for this is out of the question. The reactions are internal and take place in the metal itself or within the covering of slag, and under these, conditions carbonic oxide only can be formed. This may be subsequently burned in the furnace or regenerators, but while such combustion may decrease temporarily the amount of fuel consumed, it can have no influence on the immediate heat history of the metal.
If, however, we do assume the untenable proposition that the carbon is burned to carbonic acid (C02), then calculation shows that things are worse than before, for 333.4 kilos of ore must be added to supply the increased amount of oxygen needed by the carbon, instead of 166.7 kilos, as shown before, and this more than makes up for the extra heat produced. Under this assumption the figures for carbon are as follows:
Calories.
Heat absorbed by reducing ore...................... 40T.516
Heat created In burning to CO*.................... 304,988
Net heat absorbed............................. 102,528
Thus the reaction between oxide of iron and pig-iron in an open-hearth furnace, even when the oxide is in a fluid state, does